This practical book provides guides to the effective use of diagnostic imaging from MRI and CT scans, aiming to familiarize clinicians with the pathophysiology and how to interpret the imaging findings for making clinical decisions for obstetric and gynecological diseases. This book starts with a general introduction to explain the basics of MRI, CT, and PET/CT, written by experts in diagnostic imaging in a clear-cut style. The following parts describe the differential diagnosis of ovarian diseases, uterine tumors, and placenta and pregnancy-related　diseases. Clinicians must understand the advantages, disadvantages, and limitations of MRI, CT, and PET-CT for patient-oriented medical care. It is also essential to have the most appropriate examination at the proper time and use the diagnostic imaging in critical phases to decide the course of medical treatment. MRI and CT for Decision-Making in Obstetrics and Gynecology Practice shares tips and insights into the practical interpretation of the diagnostic imaging for obstetricians, gynecologists, and diagnostic imaging physicians to help make critical decisions in day-to-day practice. The book inspires and offers insights to promote mutual understanding and collaboration between radiologists and clinical oncologists. This is a translated version of the book originally published in Japanese language. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). The present version has been technically and linguistically revised by the author in collaboration with Dr. Takahito Niiyama, Department of Radiology, Toyama University Hospital, followed by English editing by American Manuscript Editors. .